PO-29 - Age-adjusted D-dimer Cutoff Level Increases the Number of Cancer Patients in Who Pulmonary Embolism Can Be Safely Excluded Without CT-PA Imaging: The ADJUST-PE Cancer Substudy

Introduction: Patients with cancer frequently present with suspected pulmonary embolism (PE). The D-dimer test is less useful to rule out PE in cancer patients due to a lower specificity, whereas the safety of the combination of a clinical decision rule (CDR) and D-dimer test to rule out PE in these patients is unclear. In the general population, use of an age-adjusted cutoff for D-dimer in combination with a CDR has been shown to improve specificity in the diagnosis of PE.

Aim: We prospectively analysed the safety and efficacy of the age-adjusted D-dimer (defined as age×10 in patients >50 years) combined with CDR for the exclusion of PE in patients with cancer.

Materials And Methods: We conducted a multicenter multinational prospective management outcome study in 19 centers in Belgium, France, The Netherlands and Switzerland, the ADJUST-PE study, to validate an age-adjusted D-dimer cut-off in patients with suspected PE. The performance of the age-adjusted D-dimer cut-off and CDR was compared between patients with and without cancer. The primary outcome was the rate of adjudicated thromboembolic events during three-month follow-up.

Results: Of the 3,324 patients with suspected PE, 429 (12.9%) patients had cancer. Cancer patients were older and more often had surgery or immobilisation. The prevalence of PE was 108/429 (25.2%) in cancer patients and 522/2894 (18%) in patients without cancer, p<0.001. Among cancer patients with an unlikely CDR, 27/274 (9.9%) had a D-Dimer <500 μg/L as compared with 19.7% using the age-adjusted D-dimer cut-off; in patients without cancer, these rates were 30.1% and 41.9%, respectively. The percentage of cancer patients in whom PE could be excluded based on CDR and age-adjusted D-dimer doubled from 6.3% to 12.6%. None of these cancer patients had a venous thromboembolic event during three-month follow-up, thus the failure rate was 0.0% (95% CI 0.0-6.9%).

Conclusions: Compared with the usual cut-off, the age-adjusted D-dimer cut-off doubles the proportion of patients with cancer in whom PE can be safely excluded by CDR and D-dimer without need for CTPA imaging.